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1

Analysis of the influence of electrospinning process parameters on the morphology of poly(lactic acid) fibres

Matysiak W., Kapica A, Tański T., Dubiel A.

Archives of Materials Science and Engineering

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2019

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Vol. 96, nr 2

73--78

EN

Purpose: The article focuses on the production of polymer nanofibres from poly(lactic acid) using the electro-spinning method, i.e. the technique of forming fibres in an electrostatic field. The main aim of the publication was to analyse the influence of the distance between electrodes on the morphology of one-dimensional polymeric materials obtained. Design/methodology/approach: In the practical part of the study solutions of polylactide in acetone and a mixture of chloroform/dimethylformamide (DMF) were produced. After 72 hours of mixing, no homogeneous solutions were obtained, therefore a solution consisting of a polylactide dissolved in chloroform was prepared, to which dimethylformamide was added in order to dilute the mixture. The morphology of the nanostructures obtained was analysed by means of a scanning electron microscope (SEM) equipped with an X-ray energy dispersion spectrometer (EDS), which allowed to analyse the chemical composition of the nanofibres produced. The electro-spinning method used to obtain fibres is characterized by high versatility - it gives the possibility to produce fibres from a wide range of polymers. Electro-spinning is also an economic method, and spinned fibres have a wide application potential. Findings: Nanofibres obtained by electro-spinning from the previously produced solution, regardless of the distance between the nozzle and the collector (10 or 20 cm) did not show any significant discrepancies in the values of measured diameters. Fibres obtained at increased distance between electrodes (20 cm) are characterized by a smaller average diameter value, but the difference is small, fluctuating between 48-49 nm. In the case of the sample formed during electro-spinning at the distance of the nozzle - collector equal to 10 cm and the sample produced at the distance doubled, no defects in the structure of the obtained nanofibres were observed. The analysis of topographic images of surfaces produced in the course of nanostructures' work did not show any significant influence of the distance between the nozzle and collector on the diameter of fibres. No defects in the structure of one-dimensional polymer materials obtained allowed to state that the distance between the nozzle and the collector in the range of 10-20 cm is the optimal parameter of the electro-spinning process allowing to obtain smooth, untangled fibres. Practical implications: The fibrous polymer mats obtained during the electro-spinning process of polylactide can be used as protective clothing materials, as drug delivery systems, as tissue scaffolding and as filtration membranes. Originality/value: At present, there are few articles in the literature on the electrospinning process, due to the fact that it is a constantly developing matte for the production of nanofibres. Moreover, most of the research focuses on fibres obtained from nonbiodegradable polymers, which do not have the advantages of fibres obtained from polylactide.

2

Ocena odporności na pękanie kompozytów UHTC na bazie ZrB2 otrzymanych metodą SPS oraz HP–HT

Bączek E., Naughton-Duszova A., Podsiadło M., Dubiel A.

Materiały Ceramiczne

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2018

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T. 70, nr 1

20--28

PL

W pracy badano wpływ dodatku proszków węglika krzemu i węglika boru na właściwości kompozytów ceramicznych na bazie ZrB2, stanowiących materiały UHTC (ang. ultra high temperature ceramics). Próbki z polikrystalicznego dwuborku cyrkonu, jak również kompozyty na osnowie tej fazy z dodatkiem 2% i 10% wag. SiC oraz B4C, otrzymano na drodze spiekania wspomaganego ciśnieniowo przy użyciu metody SPS/FAST (ang. spark plasma sintering / field assisted sintering technique) oraz HP–HT (ang. high pressure - high temperature). Otrzymane kompozyty scharakteryzowano pod kątem składu fazowego, mikrostruktury, właściwości mechanicznych i odporności na pękanie. Uzyskane materiały charakteryzują się wysoką gęstością względną w zakresie od 97% do 98%. Wykazano wyższą twardość oraz odporność na pękanie dla kompozytów o osnowie dwuborku cyrkonu z dodatkiem faz ceramicznych otrzymanych metodą HP–HT.

EN

The effect of the addition of silicon carbide and boron carbide powders on the properties of ZrB2 ceramic composites constituting ultra high temperature ceramics (UHTC) was investigated. Polycrystalline zirconium boride samples, as well as composites with the matrix of this phase with the addition of 2 wt.% and 10 wt.% of SiC and B4C were obtained by pressure-assisted sintering using SPS/FAST (spark plasma sintering / field assisted sintering technology) and HP–HT (high pressure -high temperature) methods. The composites were characterized in terms of phase composition, microstructure, hardness and fracture toughness. It has been stated that they had a high relative density in the range of 97% to 98%. Higher hardness and fracture toughness was observed for composites with the addition of ceramic phase obtained by HP–HT method.

3

The impact of TiN content on microstructure and mechanical properties of ceramic particulate composite Si3N4–TiN

Dubiel A., Górny G., Rączka M., Stobierski L.

Inżynieria Materiałowa

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2017

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Vol. 38, nr 5

224--230

EN

The paper presents the results of study of the influence of the volume fraction of TiN phase on the microstructure and mechanical properties of the ceramic particulate composite Si3N4–TiN. Samples of the Si3N4–TiN composite containing 5, 10, 15 or 20 vol. % of TiN phase were obtained by sintering mixtures of TiN and Si3N4 powders and sintering additives (6 wt % aluminium oxide and 4 wt % of yttrium oxide). Two types of TiN powder differing in the degree of fragmentation were used. Sintering was conducted at a pressure of 25 MPa at 1750°C for 1 hour. The resulting materials were subjected to quantitative analysis of the microstructure in order to determine the effect of TiN volume fraction and kind of TiN powder used on the microstructure of composites. Binary images showing the Si3N4 grains or TiN particles were obtained by the processing and binarization of SEM gray images of composite microstructure using the Aphelion computer software. The values of selected stereological parameters determining the size, shape and uniformity of distribution of the TiN particles and the size and shape of the matrix grains were determined. The study of the composite microstructure showed that for both types of TiN powders the increase of TiN volume fraction does not cause significant changes in size and shape of the Si3N4 grains. The increase in volume fraction of TiN phase produces the increase in the average TiN particle size in the composite, but cause only a slight change in their shape. Titanium nitride particles in the composite were smaller and somewhat more isometric and more uniformly distributed in the matrix when fine TiN powder was used. Measurements of flexural strength σf and fracture toughness KIc of all materials samples were conducted to determine the effect of composite microstructure changes on mechanical properties. The flexural strength and fracture toughness of the composites increase with the volume fraction of TiN phase. Composites with finer TiN particles are preferable from the point of view of better flexural strength, but higher values of fracture toughness are obtained for composites with coarser TiN particles.

PL

W celu doskonalenia właściwości mechanicznych ceramiki z azotku krzemu tworzy się kompozyty ziarniste o osnowie z Si3N4, a jednym z takich materiałów jest kompozyt Si3N4–TiN. W kompozytach ziarnistych istotnymi zmiennymi mikrostrukturalnymi są m.in. udział objętościowy fazy rozproszonej, wielkość i kształt cząstek tej fazy oraz sposób ich rozmieszczenia w osnowie kompozytu. Celem pracy jest zbadanie wpływu udziału objętościowego fazy TiN oraz stopnia rozdrobnienia proszku TiN użytego do wytworzenia kompozytu Si3N4–TiN na jego mikrostrukturę oraz twardość, wytrzymałość na zginanie i odporność na kruche pękanie.

4

Mechanical properties of hot-pressed Si3N4-TiN grain composites

Dubiel A.

Mechanik

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2016

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R. 89, nr 5-6

494--495

PL

W pracy zbadano właściwości mechaniczne kompozytów ziarnistych Si3N4-TiN otrzymywanych metodą prasowania na gorąco z komercyjnych proszków. Drobnoziarnisty azotek tytanu był homogenicznie rozmieszczony w mikrostrukturze spieków. Zaobserwowano poprawę wytrzymałości na zginanie materiałów. Odporność na kruche pękanie kompozytów nie uległa poprawie.

EN

Dense Si3N4-TiN composites were prepared from commercial powders using hot pressing method. Titanium nitride grains were homogenously distributed in material’s microstructure. Flexural strength of materials increased with TiN amount and reached 880 MPa. Fracture toughness of materials varied between 7 and 8 MPa m0,5.

5

Innowacja w szklanych stropach

Malawski A., Prędki M., Dubiel A.

Świat Szkła

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2013

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R. 18, nr 4

45--47

6

Automatyzacja procesów sterowania z wykorzystaniem Platformy Systemowej Wonderware

Cholewa M., Dubiel A., Kalus Ł., Zając M.

Napędy i Sterowanie

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2012

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R. 14, nr 7/8

104--107

PL

W referacie omówiono modernizację systemu sterowania kompleksu przeróbczego w ZG Sobieski PKW SA w Jaworznie. W zakres modernizacji wchodziła m.in. automatyzacja procesu granulacji, modernizacja sterowania na zagęszczaczu promieniowym Dorra, wizualizacja procesów filtracji oraz zastąpienie starej tablicy synoptycznej modułem wejść/wyjść cyfrowych. Modernizacjia odbyła się etapami, bez konieczności zatrzymywania pracy zakładu.

EN

The paper discusses about upgrading of the control system in coal preparation complex department, located in ZG Sobieski SA PKW SA Jaworzno. The modernization includes automation of granulation process, upgrade of control system at Dorra furry tank, visualization of filtration press and replacement of synoptic panel by distributed I/O module. The total scope of modernization was performed in stages, without necessary of production stoppage.